Angled Secondary Combustion Injectors for Gas Turbine NOx Reduction
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Solution Overview
Problem
Conventional gas turbine engines face a challenge in balancing operational efficiency with reduced nitrogen oxide emissions, as higher combustion temperatures increase NOx production, and existing secondary combustion systems have reliability concerns due to fuel injector placement in hot gas pathways.
Innovation Solution
A secondary combustion system with angled and variable diameter fuel/air injectors positioned downstream of the primary combustion zone, which injects fuel and air into the hot combustion gases to reduce emissions by enhancing mixing rates and flame liftoff, while maintaining efficiency and reliability through auxiliary injection systems and fuel reforming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If fuel injectors are positioned directly in the hot gas pathway to enable secondary combustion, then nitrogen oxide emissions are reduced, but component reliability deteriorates
Solution Approach 1:
A cooling gas pathway is introduced as an intermediary between the hot combustion gases and the fuel injector. This cooling gas pathway carries cooler gas from the combustor inlet region to the injector location, reducing the thermal exposure of the injector to hot gases while still allowing the injector to function in the combustion zone for emissions reduction
Solution Approach 2:
Cooling gas is pre-cooled in the cooling gas pathway before reaching the fuel injector. This preliminary cooling action reduces the temperature of the gas environment around the injector, protecting it from excessive thermal conditions while maintaining the secondary combustion function
2Productivity
If combustion stream temperature is increased to improve operational efficiency, then efficiency improves, but nitrogen oxide emissions increase
Solution Approach 1:
The combustion process is segmented into a primary combustion zone where fuel and air are premixed and combusted at controlled temperatures, and a secondary combustion zone downstream where additional fuel is injected into the hot combustion gases. This segmentation allows the primary zone to operate at lower temperatures for efficiency while the secondary zone provides additional combustion control to reduce NOx emissions
Solution Approach 2:
The system changes the temperature parameter distribution by introducing cooler gas through the cooling gas pathway to the secondary fuel injector. This creates a localized temperature modification that allows secondary combustion to occur while reducing the overall peak temperatures that lead to NOx formation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system effectively reduces NOx emissions by optimizing the mixing and combustion process, achieving improved emissions performance without compromising output or component reliability.
Implementation Method 1
A cooling gas pathway may be provided to reduce the temperature of hot combustion gases to a level more suitable for the injector
Implementation Method 2
The secondary combustion system may include a number of injectors to inject fuel and other fluids at the head end of the combustor. The fuel burns quickly due to the high temperature environment
Data Source
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AI summary
The present application provides a secondary combustion system 210 for introducing a fuel/air mixture into a flow of combustion gases in a combustor 25 of a gas turbine engine 10. The secondary combustion system 210 may include a manifold ring 230 and a number of injectors 240 extending from the manifold ring 230. Each of the injectors 240 may include a number of jets 310 in communication with the manifold ring 230. One or more of the jets 310 may include an angled configuration for the introduction of the fuel/air mixture into the flow of combustion gases at an angle.